This invention relates generally to pneumatic relays and specifically to a pneumatic relay that is capable of being reconfigured for multi-functional operation in a rapid, cost effective manner.
Pneumatic relays are in widespread use for controlling valves, actuators and the like. Basically, a pneumatic relay is a device that supplies a controlled output pressure to a load or utilization device, such as an actuator or a piston, in response to an input signal, a pressure or a force. Pneumatic relays are required to function in either a proportional or an on/off mode. In the proportional mode, a pressure output that is proportional to a pressure or force input is developed. In the on/off mode a constant pressure output, usually equal to the supply pressure, is provided for a given range of pressure or force inputs. The on/off mode of operation is often referred to as "snap action". In either of these two modes, the relay may operate in a direct or a reverse manner. Direct operation is where the output of the relay increases with increasing input, whereas in reverse operation the relay output decreases with an increasing input.
All the above functions are performed by various relays in the prior art. The distinction is, that in the present invention, a novel pneumatic relay design is disclosed in which the simple operation of a pair of mechanical port switches reconfigures the relay for proportional or snap action in either a direct or a reverse mode. The two simple position type switches are located on the relay body and may be operated manually.